Hi all, I'm taking a class in failure analysis and I need to bring something in to analyze. I wanted to bring my stripped angle gear collar sleeve but can't find it. If someone would generously donate a failed collar sleeve that would be amazing, and I will happily pay for shipping. I will upload the findings in this thread if I'm able to find a collar sleeve. Should be interesting, to my knowledge this has not been done yet.
Donate your broken angle gear collar sleeve for failure analysis?
jzs60r
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Hi all, I'm taking a class in failure analysis and I need to bring something in to analyze. I wanted to bring my stripped angle gear collar sleeve but can't find it. If someone would generously donate a failed collar sleeve that would be amazing, and I will happily pay for shipping. I will upload the findings in this thread if I'm able to find a collar sleeve. Should be interesting, to my knowledge this has not been done yet.
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I think you'd want do a cutup first to see how deep the hardening in the splines is and the analysis find the alloy its made out of before you could do anything in ANSYS to get some kind of usable data about how its failing
I don't yet know the specifics or what software because the class just started. As Houndogger mentioned we'll look at the fracture surface, determine the alloy and hardening etc... I don't believe we will be doing many simulations, just looking for clues as to how it failed and then we can speculate why it failed. Scanning Electron Microscopy will be the primary tool to determine the failure mechanism on a microscopic level, from which we can hopefully know what conditions contributed to the failure and the root cause of the failure (eg. manufacturing flaw or operating conditions). Because this is just a class I can't guarantee results, but at the very least we should come up with some interesting microscope images of the fracture surface.
This sounds like fun! I've always had an interest in failure analysis. A PhD ME at MIT used to write an article on failures for one of the engineering design magazines many years ago. His specialty was forensic failure analysis. That usually meant someone was injured, or worse. Always interesting to see the sequence of events that lead to the failure. Sometimes design, sometimes operator error, or some combination thereof.
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I think it has been done already. I remember reading some threads about physical FA and material analysis of a failed collar back when these cars were just a few years old.
From what I remember reading in those threads, the main failure mechanism is stripped splines due to fretting corrosion.
edit:
I found it - 8 pages from 2008 discussing the angle collar sleeve FA:
Volvospeed Forums
volvospeed.com
Here's the key finding:
It is apparent with the picture below that that wear is the key failure mode not an overload of the gear teeth. This is evident by the lack of grain flow in the core area near the teeth, the grain flow at the edge of the teeth, and lack of stress cracks within any part of the gear.
This is very interesting, thanks for that! It sounds like this has been pretty well established that the collar sleeves fail due to fretting. It sounds like there are two proposed causes of the problem, insufficient lubrication and poor material choice (too soft).I think it has been done already. I remember reading some threads about physical FA and material analysis of a failed collar back when these cars were just a few years old.
From what I remember reading in those threads, the main failure mechanism is stripped splines due to fretting corrosion.
edit:
I found it - 8 pages from 2008 discussing the angle collar sleeve FA:
Volvospeed Forums
Here's the key finding:
It is apparent with the picture below that that wear is the key failure mode not an overload of the gear teeth. This is evident by the lack of grain flow in the core area near the teeth, the grain flow at the edge of the teeth, and lack of stress cracks within any part of the gear.
Probably a harder metal choice would also have prevented failure, but I noticed some wear on my angle gear splines so I wonder how that would work out for the angle gear. I didn't see any discussion of corrosion, but I haven't looked through all 8 pages. Its probably safe to assume that some corrosion occurred, I'm also curious the extent to which corrosion contributes to failure. I'm guessing if the sleeve could be properly lubricated it would prevent fretting and corrosion and last a lot longer.
P.S. I no longer need a collar sleeve, I ended up finding my old stripped collar sleeve, so will do some failure analysis on it hopefully. If anything interesting comes up I will post it here
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